We have a 20 kg Spade on our B39 2006. No problem with fitting on the bow roller and it sets and holds very well. The retaining pin which secure the Bav CQR copy won’t work but I had 2 plates made to raise the pin over the top of the anchor stock and this works well. We also always tie off the anchor to the pad eye in the anchor locker.
Lazy Pelican is ashore at Ionian Marine, Preveza, if you want to have a look.
John